You can buy water heaters from any home hardware store.
GE and Rheem both produce energy efficient water heaters. They each sell different sizes and models. Rheem produces tankless electric water heaters that are affordable and energy efficient.
You can purchase water heaters at any home improvement store like Lowes or Home Depot.
I have no experience in this, however A. O Smith claims that there brand of gas water heaters are the most efficient. They also offer a hybrid water heater.
Water heaters can range from 1 unit to 10 units.
Rheem provide a series of high efficiency gas water heaters. Several different companies also provide tank-less water heaters, which are very efficient, as well as solar water heaters.
Tankless water heaters are more energy and cost efficient than your typical water heaters. Of course, each person has their own needs and it is always a good idea to weigh out the pros and cons before making any decisions for a change. What works well for some may not work well for other.
Lasko space heaters use about 800 Watts and are very energy efficient, along with being very powerful.
Rheem tankless water heaters are special since they are both energy efficient, and space saving. These water heaters are also innovative due to their small size, since they can fit under sinks and small cabinets.
Indirect water heaters are one of the most energy efficient, low cost water heaters on the market today. It stores 40 gallons of water for the cost of $0.05 per day.
No,they are not cost efficient. Bradford water heaters aren't worth the cost because replication parts are very hard to find and they don't come with refund or warranty.
Gas heaters are much more efficient. Electric resistance heaters are, by nature, hideously inefficient.
The most energy efficient pool heaters are solar heaters. You can find solar pool heaters made by Vortex, SunHeater and EcoSun amnong other companies. For non-solar powered you will want to check out pool heaters by Hayward and Pentair.